Effects of Heat on Structures of Cotton, Polyester, and Wool Fibers in a Triblended Fabric With and Without Flame Retardant

Abstract

Fabrics marketed as flame resistant are often blends of more than one fiber. The effect of flame-resistant finishes and of heat on different fibers is not the same. A previous study compared differences in morphology of cotton and polyester fibers, and of cotton and wool fibers in two blended fabrics before and after heating. This report shows, using scanning electron microscopy (SEM), the progressive changes that occur during stages of heat stress in fibers in a triblended fabric. Samples of a cotton, polyester, and wool (60/25/15) triblend, unfinished and finished with bis[tetrakis(hydroxymethyl)phosphonium] sulfate (THPS), urea, and trimethylolmel amine, were studied before and after burning. The SEM examination compares re sponses of each fiber to heat and shows that of the treated fabrics, polyester responds first by melting, wool bubbles and flows, and the external structure of cotton is relatively unchanged. Energy dispersive x-ray analyses show the location of the flame retardant agent in cotton and wool fibers. Thermal analysis data are correlated with these struc tural changes.